In the operation of a load lifting machine such as an overhead hoist or a self-propelled crane, a safety hazard warranting due attention is that of overloading the machine or attempting to raise and handle a load which is beyond the rated capacity of the machine or machine components. Such overloading is apt to result, for example, in component failure of the lifting equipment. In order to warn of impending overload, various overload indication and protection devices have been devised, as those in Hawkins et al. U.S. Pat. No. 3,728,502 issued Apr. 17, 1973 and Sandberg U.S. Pat. No. 3,802,379 issued Apr. 9, 1974. Such devices, for example, employ electric circuitry to shut off the power to the electric hoist motor when an overload condition is sensed, thus preventing use of the hoist beyond overload capacity. An overload condition can be sensed by calibrated rupture of a component, such as a shear pin, which must then be replaced to again render the machine operable. Meantime, a load can be perilously suspended on the load line of the machine. These devices are typically complex and expensive. Many require a load readout device, as a gauge, located remote from the load. The operator must divert his attention from the load and load line to read the device.
Generally speaking, the larger the load to be lifted, the greater the care and accuracy exercised in estimating the load to be lifted, and consequently, a less chance of accidental overload. For example, if a 25 ton load is to be lifted, the care exercised in estimating the load to be lifted is much greater than if a 2 ton load is to be lifted. Thus, the greater propensity to overload occurs in the use of the smaller lifting machines as the 1/2 to 5 ton capacity range which are typically not equipped with sophisticated and expensive load indicating equipment. These smaller lifting machines serve, for the most part, as universal tools, being called upon to lift a large variety of loads and perform a large variety of jobs. A load indicator for such machines should be readable by the operator without removing his attention from the load and load line. Types of lifting members employed by these machines vary considerably, from a single hook to a duplex hook, a jaw and eye swivel, and the like. It is beneficial, therefore, to provide a load indicating device usable also with larger lifting machines, but particularly adapted to these smaller machines which are more prone to overload. The device must be informative and easily read, yet compact and adaptable for use with a variety of differing lifting configurations. Further, the device should withstand overload, as is sometimes occasioned by accelerating or handling a load, without being rendered inoperable.